Melanoma

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introducedon :

  • Melanoma is a malignant tumor developed at the expense of the melanocytes (melanocytes which are arranged in the normal state of isolation between keratinocytes of the dermo- epidermal are responsible for producing a pigment for protecting the skin vis-à-vis the ultraviolet radiation : melanin, they have a ubiquitous distribution : cutaneous, mucous, retinal)
  • Sun exposure, clear skin type and the presence of large numbers of nevi are recognized risk factors
  • Its diagnosis is based on clinical, helped by dermoscopy and confirmed by histology
  • Early diagnosis and proper removal are key to the prognosis in the primary stage
  • Prognostic markers are especially histological
  • Prevention is based on changing risk behaviors, early detection and resection of suspicious lesions

Épidémiologie :

  • Incidence : doubles every 10 years in countries with white population living in sunny area, in most European countries, the incidence is estimated to 5-10 new cases / 100,000 inhabitants / a. This incidence peaked (40 new cases / 100,000 / year) among whites in Australia, while it is very low in countries where the subjects are black or yellow
  • Age from survenu : This is a tumor that affects all ages, outside of the child, at which melanoma is exceptional
  • Sex-ratio : female
  • In Algeria : a retrospective study 1985 at 1995 from 116 patients showed : higher incidence in Western countries (53.17%),  age :  40-50  years (33.80%),  sex :  55.70%  women,  nodular appearance (74.31%), seat : legs (55.70%), terrain : again (82.07%), consultation is late, Clark level : V (47.91%)
  • Melanoma mortality is high hence the importance of early diagnosis and effective surgical treatment for better prognosis
  • factors etiological : Melanoma occurs due to the interaction between individual susceptibility factors and environmental factors

factors individual :

  • Phototype : the sensitivity of the skin to sunlight is defined by the phototype. The light-skinned and blond hair and especially red are the most sensitive to the sun (phototype I/II), the more the subject is clear (no or very little melanin pigments) more likely it is UV radiation. The peak incidence of melanoma occurs in the redhead
  • phenotype naevique : that is to say the number, the size and appearance of nevus

Syndrome of nevus atypical : particular form, defined by the presence in large numbers of nevi (> 50), often large (> 6 mm), with atypical aspects (irregular edges, polychrome). These subjects will be carefully monitored because of the risk of developing melanoma

nevus congenital giant : exists at birth, it covers a part of the body of the newborn or his entire body

Postman familial : about 10% melanomas occur within a context of "familial melanoma",  defined as at least 2 generations of 3 melanoma,  prompting the identification of the family susceptibility gene melanoma

factors environment (sun exposure) : the sun is the only environmental factor involved in the epidemiology of melanoma. On distingue :

  • Exposition acute intermittent : like sunburn during childhood, is complicated melanoma in young adults,  it appears on the areas concerned by sunburn (From, shoulder, leg)
  • Exposition chronic and progressive : melanoma in the elderly, Melanoma develops on areas continuously exposed to the sun (cephalic end : melanoma lentigo)
  • Melanomas palms, plants and mucous membranes are not directly related to sun exposure

Other factors :

  • Immunodépression : promotes melanoma occurrence (kidney transplant, treatment with cytotoxic immunosuppressive ...)
  • Troubles from the repair from l’ADN : as in the Xeroderma pigmentosum, is accompanied by a high risk (x 1000)

➢ So, melanoma risk markers :

  • family and personal history (The same causes produce the same effects) melanoma
  • light colored skin and hair, especially the red marker with freckles, hair blond roux
  • High number of nevi, the risk increases with the number of nevi and atypical nevus syndrome represents the extreme of naevique phenotype at risk
  • History of intense sun exposure during leisure with sunburn
  • precursors : the majority of melanomas originate from new, skin, apparently, healthy without precursor, the risk of malignant transformation of small common nevus is very low, the congenital nevi have a higher risk of transformation if they are large (> 20 cm), they are few and, Therefore, do not cause the occurrence very little melanoma. There is no interest in the single common systematic preventive excision of nevi resection for early prevention of major congenital nevus is desirable

Diagnostic positive :

  • The diagnosis of melanoma, suspected clinically by inspection, sometimes assisted by a dermatoscope is confirmed by pathological examination, which also determines the initial therapeutic decision and assessment of prognosis
  • Suspicion : iS clinical

Rule ABCDE :

  • A : Asymmetric
  • B : Ragged edges, often notched or polycyclic
  • C : inhomogeneous color (brown, noir, brown or blue, depigmented areas, halo inflammatory)
  • D : Diameter > 6 cm
  • E : ongoing development, documented (extension in size, in shape, embossed, in color)

➢ An itching or bleeding in contact are also possible when the tumor progresses

➢ A different lesion other nevi of the subject (sign of the "ugly duckling") is suspicious

➢ Any suspicious melanoma lesion should be excised for histopathological examination

  • Diagnostic : is histological, only histological analysis to confirm the diagnosis of melanoma, it must be performed on a piece of complete resection carrying lesion in its entirety as well as the banks

Histogenèse of melanoma : takes place on a biphasic :

  • In a first phase, the extension is horizontal intraepidermal, above the basal membrane
  • In a second phase, the extension is vertical, with invasion of the superficial dermis (phase micro-invasive) then the deep dermis and hypodermis (phase invasive). Melanoma therefore, in good standing :

component intraepidermal : made of melanocytes that form a sheet or thecal irregularly arranged along the basal, associated with an invasion of the superficial layers of the epidermis by tumor cells migrating in isolation and uncontrollably

component   dermal :   invasive,   sometimes associated with an inflammatory reaction

➢ Histological examination enables :

  • To affirm the nature melanocytic from the tumor : melanin pigment, disposition, immunohistochimie…
  • To affirm the malignancy from the tumor : a number of architectural and cytological criteria for the proposition malignancy of the lesion, c & rsquo; is to say,, to distinguish between nevi and melanoma : architectural disorder, presence of atypia nucleo-cytoplasmic, d’images mitotiques, vascular emboli, a neurotrophic extension or loss of morphological gradient usually observed in nevi of the surface to the depth

➢ The pathological report should specify, for each lesion, a number of parameters that :

  • To estimate prognosis :

Indice de BreslowIndex from Breslow : it represents the measurement in millimeters, under an optical microscope, of the maximum thickness of the granular layer of the epidermis and above the deepest melanoma malignant cell. Melanomas which do not invade the dermis are not measured and are called " in situ », and there is an almost linear correlation between tumor thickness and the average time of survival

  • Specify the completeness or not of excision

Exam dermatoscopique (epiluminescence) : is a non-invasive complementary examination method that uses a symptomatology its own, based image analysis observed a whole and facilitates the differential diagnosis but dependent operator and be subject to pitfalls

Classification anatomopathologique :

On distingue 4 major types of melanoma, according to their clinical and histopathological appearance and their mode of progression

  • Melanoma Superficial Extensive (SSM : Superficial Spreading Melanoma) : represented 60-70% melanoma, it is in the form of a pigmented macule may secondarily take terrain with appearance of a nodular component. This seat melanoma most commonly the lower limb in women and back in men. The horizontal growth phase above, in general, vertical phase of several months
  • Melanoma nodular : represented 10-20% melanoma, it appears from the outset as a nodule and is growing rapidly. Its development is at once vertical (without horizontal phase) and metastatic risk is important, so it leaves little time for screening a thin stage (poor prognosis)
  • Melanoma from Freckle (lentigo malin) : which represents 5-10% melanoma, he sits, predilection, on sun-exposed areas (face, neckline, forearm) and occurs in the elderly. The clinical appearance is that of a macula and a pigmented web, which has a horizontal development for months and years, thus leaving plenty of time for dermal excision before invasion
  • Melanoma acral lentigineux (acrolentigineux) : which represents 2-10% melanoma in the subject white and up 60% melanoma in the black patient. The clinical appearance is that of a pigmented macule who sits in a privileged manner at the ends (palms, plants, fingers, toes), horizontal growth phase is generally very slow and leaves a lot of time for a removal before dermal invasion

shapes clinics special :

  • Melanoma of the mucous : it represents 5% of all melanomas, it's about, in general, Late diagnosis of melanoma and poor prognosis, and more so that the tumor probably faster access to a lymph drainage (vulvar melanoma, melanoma of the nasal cavities, anorectal melanoma ...)
  • Melanoma from l & rsquo; child : it is exceptional and its diagnosis is difficult, indeed, false melanoma diagnoses correspond,  in fact,  Adaptable inflammatory nevus. Melanomas of the child most often occur again, Congenital melanomas are exceptional
  • Melanoma achromique : these melanomas that are not pigmented are generally in the form of a pink or red lesion, their diagnosis is difficult because they can simulate a number of lesions (basal cell carcinoma, botryomycome…). Their prognosis is usually grim : firstly because of frequent late diagnosis, secondly because they are readily forms nodular rapid growth
  • Melanoma nail : belongs to the group of melanomas acrolentigineux, which has the same epidemiological and prognostic features. preferential seat : big toe or thumb, aspect : brown or black macula in the nail bed and under the nail fold (Hutchinson's sign), band mélanonychique,  longitudinal acquired,  nail dystrophy,  matrix destruction,  ulcerated tumor, hence the importance of biopsy

Diagnostic differential :

He must rule out other black tumors are much more common than melanoma

  • Tumors melanocytic : Clinically atypical nevi have aspects sometimes the criteria beginners melanoma, freckles ...
  • Tumors nonmelanocytic : on distingue :

Kératoses  seborrheic :  usually multiple lesions,  sitting on the seborrheic areas of the face and trunk, the clinical aspect is yellowish lesions, brown or black frankly, the warty surface and screened keratotic plugs (lesions placed on the skin). The differential diagnosis with melanoma is usually easy, dermoscopy makes it easy to rectify the diagnosis in difficult cases

Carcinoma basal cell tattooed : it can be confused with a SSM or a nodular melanoma, the beaded appearance of the lesion or the presence of telangiectasia can guide the diagnosis, dermoscopy may also be useful

Histiocytofibrome pigmented : nodular lesions, strictly intradermal, can be pigmented, palpation of these lesions is quite characteristic (indurated pellet) usually allows correct diagnosis

Hémangiome :  it can take a bluish or black when irritated or thrombosed, dermoscopy is also characteristic

Botryomycome : it may pose a diagnostic problem with nodular melanoma amelanotic, its occurrence after trauma may help diagnosis

Hematoma undernail : it is usually easy to distinguish from melanoma in- nail. When in doubt,  resection should be made to have a histological confirmation of the exact nature of the injury

Fibroma mou (molluscum pendulome)

ISevolution :

  • The usual spontaneous evolution is marked by local invasion with a possible extension to the adjacent skin or remotely, to regional lymph nodes and metastases, usually multiple (soft tissue, lung, foie, brain, the…)
  • The majority of metastases occurs between 2 and 5 years after treatment of primary tumor

criteria clinics and histopathological of prognosis (poor prognostic factors)

  • Occurrence of melanoma in later life
  • Occurrence of melanoma in humans (male)
  • Location of the cephalic melanoma and melanoma of mucous membranes have a poor prognosis (because of early node-positive)
  • Type anatomoclinique (nodular melanoma has a poor prognosis)
  • Existence of ulceration (clinical or histopathological)
  • Existence of a nodal
  • Existence of metastases and their number
  • The main prognostic factor independent of melanoma all other factors : tumor thickness (indice Breslow) with an almost linear correlation between thickness and mortality

Traitement :

  • Outside of surgical treatment which can be, in some cases, a cure, other treatments are palliative
  • The goal of treatment is to ensure the longest possible survival and avoid locoregional recurrence and cutaneous metastases, lymph node and visceral

Surgical : surgical excision must be early, stage non-invasive, allows for healing

  • At the stage of lymph node involvement or metastases, Treatment will involve surgical removal of the melanoma followed by resection of metastases when possible

Chemotherapy : various drugs and protocols are used but melanoma remains insensitive to chemotherapy

Radiotherapy : finds use in the event of node or metastatic disease

biotherapy and vaccination antitumor : appear to be promising ways

Prévention :

  • Prevention primary (risk reduction) : through informing the population about the risk associated with sun exposure and the reduction of these exposures (limiting exposure to strong sunlight hours more,  protective clothing and repeated use photo- external protective), it is intended primarily for children but is important at all ages, so there is no interest in the systematic preventive excision common nevus, only early preventive excision of large congenital nevus is desirable
  • Prevention secondary (screening) : must be early to improve prognosis, indeed, plus one melanoma is detected late, the greater the risk of invasive (vertical phase) and metastasize. Physicians should consider the integument know their patients in its entirety and should identify suspicious pigmented lesions, the general public should know the warning signs that should prompt visit, high-risk families should be given special medical supervision, risk subjects should be informed and subjects at very high risk (first melanoma,  atypical nevus syndrome)  must have a specific healthcare monitoring (photographic, dermatoscopique)

Conclusion :

  • Melanoma is an aggressive tumor, the significant metastatic potential, so the incidence is increasing
  • The wide surgical resection at an early stage is the only potentially curative treatment since the metastatic potential is important and no therapy is currently effective at this stage
  • The major prognostic factor is constituted by the Breslow
  • Patient information (to change the solar risky behavior) and detection of suspicious lesions are the basis for the prevention